How Lasik Works

LASIK eye surgery can be a liberating experience for people hoping to reduce or eliminate their dependence on glasses and contact lenses. Most patients do not realize how evolved LASIK eye surgery has become in recent years. The level of technology has been improving this amazing eye surgery since its FDA approval in 1995. In order to better explain all of the dimensions of LASIK surgery we want to briefly highlight the different types of LASIK surgery and what their significance actually is to your vision correction decision. We hope you might find this information useful in your research process. Northwestern Medicine LASIK Physicians aim to provide only the most credible LASIK eye surgery information. This is critical to determine the best vision correction procedure for your unique eyes.

About LASIK laser vision correctionLASIK stands for Laser in-situ keratomileusis, which is the most commonly performed type of laser eye surgery today. This eye surgery procedure is generally safe, effective, and has very few side effects. LASIK is a great option for many individuals considering laser vision correction for a variety of very personal and professional reasons. LASIK eye surgery may not promise perfect vision, however; it is a highly successful procedure that can at the very least reduce a person’s dependence on glasses or contact lenses. The lifestyle benefits can be tremendous for active and social people. These benefits can enable people to more freely pursue their hobbies, sports activities or career options. LASIK has been performed in the United States since its FDA approval in 1995. At the 2005 AAO (American Academy of Ophthalmology) meeting a 10 year study of the effectiveness and safety was presented and showed overwhelming success of the procedure. If LASIK eye surgery is something that you think might help your vision please feel free to call us anytime or complete our LASIK self-evaluation TEST and one of our LASIK eye surgery coordinators will contact you.

The Excimer LaserWhen you hear the word laser, you are probably wondering how can this possibly help in correcting vision. The laser responsible for all of this eye surgery is commonly known as the excimer laser. There are many brands of excimer lasers on the market today and some of them have specific points of differentiation. For an explanation of the excimer laser of choice for Northwestern Medicine LASIK Physicians visit our page on LASIK technology. The excimer laser's role is to permanently change the shape of the cornea, or the outer layer of the eye. The excimer laser, which is a specific type of "cool" laser, generates its power from light in the ultraviolet range. This cannot be visualized by the human eye. Because the laser does not generate any heat, there is no tissue damage as the result of the laser light. As the treatment with the laser proceeds, microscopic layers of tissue, approximately 1/10th the width of a human hair are removed. The laser is programmed to remove precisely the amount of tissue needed to achieve the desired result.The LASIK Procedure(ALSO known as laser vision correction)During LASIK, the surgeon first applies anesthetic eye drops to numb the eye for surgery. The cornea is then marked with water-soluble ink to guide replacement of the flap. Next a suction ring is applied that is designed to hold the eye steady and also confirms the pressure of the eye. The surgeon then creates a thin corneal flap using IntraLase laser. The surgeon tests for laser alignment and walks the patient through the fixation process. The corneal flap is lifted up, and the laser beam is applied to the exposed interior surface of the cornea to reshape the tissue. The computer-controlled excimer laser removes the tissue under the flap and reshapes the cornea of the affected eye. In less than 60 seconds, high-energy pulses from the excimer laser actually reshape the internal cornea with accuracy up to 0.25 microns, or 1/4000 of a millimeter. The flap is then replaced over the treated area. This corneal flap serves as a natural bandage, which eliminates the discomfort associated with other types of refractive surgery, and expedites the healing process. Your doctor will then watch the eye for five minutes to ensure proper healing. Because of the extraordinary bonding properties of the corneal tissue, sutures are not needed to keep the flap in place post-operatively.

Different types of LASIK eye surgery

Conventional LASIKThe original form of LASIK eye surgery where the IntraLase laser is used to make a flap. Once the flap is made the excimer laser is used to correct the shape of the cornea. Conventional LASIK does not include wavefront technology, also known as "Custom LASIK."

Custom LASIKAll eyes suffer from optical aberrations or distortions. Aberrations can be separated into two categories HIGH and LOW. Low order aberrations are the familiar sphere and cylinder of myopia, hyperopia, and astigmatism, measured through refraction and denoted by diopters on your prescription. This is precisely what conventional LASIK was aiming to correct. Higher order aberrations such as trefoil, coma, and other similarly unfamiliar terms cannot be measured with a standard refraction. Instead, they are measured with an instrument called an aberrometer. The aberrometer measures the total amount of aberrations in the eye, including the refraction, and then transforms this complex data into a wavefront map. Aberrometer findings are transferred and then loaded into the excimer laser for treatment. The laser ablation pattern to improve your vision is derived from the total set of aberrations. For more information regarding Custom LASIK or wavefront technology visit our Custom LASIK page.Monovision LASIKMonovision LASIK is a surgical technique in which one eye is corrected for distance vision and the other eye is corrected for up close vision or reading vision. This version of LASIK is typically performed only on patients over the age of 40 years old and is the only way that an older patient can avoid needing reading glasses. Many people that undergo Monovision LASIK are satisfied with their new vision. Despite the relatively high level of patient satisfaction we typically ask each patient to undergo a contact lens trial prior to having the actual surgery because this will give the most realistic view of what Monovision will be like. Monovision is not for everyone so make sure to consult one of our LASIK experts.Blade-FREE LASIKTraditionally, a microkeratome is used to create the corneal flap necessary in LASIK eye surgery in Chicago. Ophthalmologists have found that when complications arise from LASIK they are typically from a poorly created corneal flap. Unlike mechanical instruments, IntraLase technology (Blade-FREE LASIK) is uniquely able to program the dimensions of your flap based on what's best for your eye(s). Then the IntraLase laser (femtosecond laser) creates your flap from below the surface of the cornea-without ever cutting it. This process is done in a series of steps:

Ultra-fast pulses of laser light position microscopic bubbles at a precise depth predetermined by your doctor.

The laser light passes harmlessly through your cornea. Then the laser creates rows of these bubbles just beneath your corneal surface as it moves back and forth across your eye in a uniform plane.

Next, the IntraLase laser stacks bubbles around your corneal diameter to create the edges of your flap. These bubbles are stacked at an angle that is determined by your doctor and is individualized to the way your eye is shaped.

The LASIK doctor will then gently lift the flap to allow for the second step of your LASIK treatment. When treatment is complete, the flap is gently put back into position and the healing process begins.

For more information on Blade-FREE LASIK also known as Intralase IFS (femtosecond laser) surgery visit our page on Blade-FREE LASIK in Chicago.

PRK (Photo-Refractive Keratotomy)

PRK is similar to LASIK, in that the same type of laser is used; however a corneal flap is not created. Instead, the laser beam is applied directly to the surface of the eye to reshape the cornea. PRK is less frequently used because of the development of LASIK, but in some individual cases, PRK may still be the procedure of choice.

Even though the initial healing may take several days longer than that of LASIK, the long-term results are the same.

LASIK RisksNo matter what type of LASIK you and your surgeon decide is right, you must understand that there are risks. LASIK is a surgical procedure conducted on the cornea. It is crucial that patients are well educated on the potential benefits and risks of this procedure. After your pre-operative evaluation you will have a good idea about the risks and what they imply to your specific situation. It is important to discuss any concerns with directly with your surgeon. Each patient’s vision is different and different treatment options are available in order to give the best possible results. Once again, the only way to determine if LASIK is right for you is to come in and discuss your options with our LASIK coordinator.

Understanding Re-treatmentsWhen is a LASIK or PRK re-treatment or touch up necessary?Be sure to discuss the topic of LASIK re-treatments with your Northwestern Medicine LASIK Physician. Re-treatments, also called enhancements, may be required to achieve optimal outcomes. Fortunately, it is possible to repeat the laser treatment by lifting the flap, typically about three months after the original procedure.